1. Field of the Invention
The invention is directed to a key and a rotary locking cylinder as well as to a key for a rotary locking cylinder with an additional tumbler.
2. Background Art
The advantage of keys of this generic type is that the control element arranged in the shank virtually prevents unauthorized copying so that locking arrangements outfitted with such keys are more secure. However, known keys of this type, also called "mechanical keys", are still subject to various disadvantages and so have not achieved widespread use, particularly as turning keys, in spite of their very high security against copying.
A key of this generic type is known, for example, from DE-A-35 17 660. This key can be inserted into the key slot of a rotary locking cylinder and has, in its planar shank, a movable device by means of which an additional tumbler can be moved into the releasing position. The movable device of the key is formed by a projecting pin which can be held displaceably in a pocket hole of the key. Also arranged in the pocket hole is a spring which presses the pin outward. The pin is prevented from falling out by steps in the pocket hole of the shank and at the pin. Projecting pins are generally disadvantageous in a key, as the key easily becomes caught on the pin.
Another key of this type having a pin which can be displaced in a defined manner for the purpose of bringing into line the additional tumbler in the shank is known from U.S. Pat. No. 4,667,495. When the shank is inserted into the key slot, the pin runs up onto an inclined plane or ramp arranged in the rotor. The ramp displaces the pin radially and the pin accordingly brings the additional tumbler into line. Grooves or other recesses are required at the shank to allow the ramp to reach the pin when the shank is inserted. In the case of a flat key, these grooves limit the surface available for control bore holes. Therefore, in practice, the pin must be arranged as close as possible to the front end of the shank. One end of the easily displaceable pin usually projects out at the shank so that the key can also become caught on this.
A key of this type is also known from EP-A-202 949. The additional tumbler is likewise brought into line in this instance by a pin which is displaceable in a defined manner in the key shank, resulting in the difficulties mentioned above.